Heat exchanger including heat-transfer-tube unit

ABSTRACT

A heat exchanger includes a heat-transfer-tube unit and a header. The heat-transfer-tube unit includes a fin and heat transfer tubes. The header is connected to the heat-transfer-tube unit. The fin and the heat transfer tubes are disposed, alternately, side by side, where the heat transfer tubes extend in a heat-transfer-tube-extending direction. The fin has sides that extend in the heat-transfer-tube-extending direction and that are joined to the heat transfer tubes. An end of the fin is disposed closer to a center of the heat-transfer-tube unit in the heat-transfer-tube-extending direction than ends of the heat transfer tubes, and the ends of the heat transfer tubes are inserted into holes disposed on the header.

TECHNICAL FIELD

The present invention relates to a heat exchanger including a heat-transfer-tube unit.

BACKGROUND

Some of heat exchangers intended for air conditioners and the like include heat-transfer-tube units each formed as a single member including heat transfer tubes for refrigerant to flow therein and fins for heat exchange. A heat exchanger disclosed by PTL 1 (Japanese Unexamined Patent Application Publication No. 2013-139965) includes a plurality of such heat-transfer-tube units. The plurality of heat-transfer-tube units are connected to a shared header.

The connection is simplified by dividing the header into many layers. The heat exchanger is manufactured by alternately stacking the divided header layers and the heat-transfer-tube units. Then, the stack of the divided header layers and the heat-transfer-tube units is brazed in a furnace so that leakage of refrigerant from joints between the divided header layers is prevented.

[PTL 1] Japanese Unexamined Patent Application Publication No. 2013-139965

The heat exchanger configured as above with many divided header layers has an increased number of components. Therefore, the process of manufacturing the heat exchanger is complicated.

SUMMARY

One or more embodiments of the present invention provide a heat exchanger that is easy to manufacture.

A heat exchanger according to one or more embodiments of the present invention includes a heat-transfer-tube unit and a header. The heat-transfer-tube unit includes at least one fin and a plurality of heat transfer tubes. The heat-transfer-tube unit is connected to the header. The fin and the heat transfer tubes are arranged alternately side by side. The plurality of heat transfer tubes each extend in a heat-transfer-tube-extending direction. The fin has sides extending in the heat-transfer-tube-extending direction and that are joined to the heat transfer tubes. An end of the fin is positioned nearer (closer) to a center of the heat-transfer-tube unit in the heat-transfer-tube-extending direction than ends of the heat transfer tubes. The header has holes for insertion of the ends of the heat transfer tubes.

In such a configuration, the ends of the heat transfer tubes project from the end of the fin. Therefore, the heat exchanger can be manufactured easily by inserting the projecting portions of the heat transfer tubes into the holes in the header.

In a heat exchanger according to one or more embodiments of the present invention, the header includes a first header and a second header between which the heat-transfer-tube unit is held.

In such a configuration, the two ends of the heat-transfer-tube unit are fixed to the respective headers. Therefore, the heat exchanger exhibits improved durability against external forces and impacts.

In a heat exchanger according to one or more embodiments of the present invention, the second header is positioned below the first header. The second header has a heat-transfer-tube-unit-connecting surface inclined with respect to a heat-transfer-tube-spacing direction.

In such a configuration, the heat-transfer-tube-unit-connecting surface of the second header is inclined. Accordingly, dew condensation water running down the heat-transfer-tube unit and reaching the heat-transfer-tube-unit-connecting surface further runs down the second header because of the inclination. Therefore, the heat exchanger exhibits improved drainability.

In a heat exchanger according to one or more embodiments of the present invention, the header is a circular pipe.

In such a configuration, since the header is a circular pipe, the header is easy to manufacture. Therefore, the heat exchanger can be manufactured more easily.

In a heat exchanger according to one or more embodiments of the present invention, the end of the fin is shaped in conformity with a shape of the header in such a manner as to be in contact with the header with the ends of the heat transfer tubes being in the holes.

In such a configuration, the end of the fin is in contact with the header. Therefore, the heat-transfer-tube unit and the header are connected to each other with improved strength.

In a heat exchanger according to one or more embodiments of the present invention, the end of the fin is spaced apart from the header.

In such a configuration, the occurrence of a phenomenon in which brazing metal moves into a space between the fins by capillarity can be suppressed.

In a heat exchanger according to one or more embodiments of the present invention, the heat-transfer-tube unit includes stoppers. The stoppers are provided on the heat transfer tubes and between the ends of the heat transfer tubes and the end of the fin. The stoppers are each shaped in such a manner as not to be allowed to pass through the holes in the header.

In such a configuration, the occurrence of the phenomenon in which the brazing metal moves into the space between the fins by capillarity can be suppressed further.

In a heat exchanger according to one or more embodiments of the present invention, the heat-transfer-tube unit is a single member.

In such a configuration, the heat-transfer-tube unit is a single member. Therefore, the heat-transfer-tube unit is easy to handle. Accordingly, the heat exchanger is easy to assemble.

A heat exchanger manufacturing method according to one or more embodiments of the present invention includes forming a heat-transfer-tube unit including a fin and heat transfer tubes; providing a cutout by removing a portion of the fin such that an end of the fin is positioned nearer to a center of the heat-transfer-tube unit in a heat-transfer-tube-extending direction than ends of the heat transfer tubes; providing holes in a header, the holes being provided for insertion of the ends of the heat transfer tubes; inserting the ends of the heat transfer tubes into the respective holes; and brazing the heat-transfer-tube unit and the header to each other.

In such a method, since the cutout is provided by removing a portion of the fin, the ends of the heat transfer tubes project from the end of the fin. Therefore, the heat exchanger can be manufactured easily by inserting the projecting portions of the heat transfer tubes into the holes in the header.

In a heat exchanger according to one or more embodiments of the present invention, the forming the heat-transfer-tube unit includes integrally forming the fin and the heat transfer tubes from a metal material by extrusion molding.

In such a method, the heat-transfer-tube unit is formed as a single member from a metal material by extrusion molding. Therefore, the heat-transfer-tube unit is easy to handle. Accordingly, the heat exchanger is easy to assemble.

In a heat exchanger according to one or more embodiments of the present invention, a plurality of portions of the fin are punched off in the providing the cutout.

In such a method, the plurality of portions are removed by punching. Therefore, the heat exchanger is manufactured efficiently.

In a heat exchanger according to one or more embodiments of the present invention, the holes are provided by drilling in the providing the holes.

In such a method, the holes in the header are provided simply by using a drill. Therefore, the heat exchanger is manufactured more easily.

One or more embodiments of the present invention provide a heat exchanger that can be manufactured easily.

One or more embodiments of the present invention provides a heat exchanger that exhibits improved durability against external forces and impacts.

One or more embodiments of the present invention provides a heat exchanger that exhibits improved drainability.

One or more embodiments of the present invention provides a heat exchanger in which the heat-transfer-tube unit and the header are connected to each other with improved strength.

One or more embodiments of the present invention each provide a heat exchanger in which the occurrence of a phenomenon in which brazing metal moves into a space between the fins by capillarity can be suppressed.

One or more embodiments of the present invention each provide a heat-exchanger-manufacturing method by which a heat exchanger can be manufactured easily.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an outline of a heat exchanger 10 according to one or more embodiments of the present invention.

FIG. 2 is a diagram illustrating an outline of a heat-transfer-tube unit 30 according to one or more embodiments.

FIG. 3 is a sectional view of the heat-transfer-tube unit 30 according to one or more embodiments.

FIG. 4 is a sectional view of part of the heat exchanger 10 according to one or more embodiments.

FIG. 5 is a sectional view of part of a heat exchanger 10′ according to one or more embodiments of the present invention.

FIG. 6 is a sectional view of part of a heat exchanger 10″ according to one or more embodiments of the present invention.

FIG. 7 is a sectional view of part of a heat exchanger 10A according to one or more embodiments of the present invention.

FIG. 8 is a sectional view of part of a heat exchanger 10B according to one or more embodiments of the present invention.

FIG. 9 is a sectional view of part of a heat exchanger 10C according to one or more embodiments of the present invention.

FIG. 10 is a diagram illustrating an outline of a heat exchanger 10D according to one or more embodiments of the present invention.

FIG. 11 is a diagram illustrating an outline of a heat-transfer-tube unit 30 according to one or more embodiments of the present invention.

DETAILED DESCRIPTION (1) Overall Configuration

FIG. 1 illustrates a heat exchanger 10 according to one or more embodiments of the present invention. The heat exchanger 10 is provided for heat exchange between refrigerant and air and is to be included in, for example, an air conditioner. The heat exchanger 10 includes a first pipe 41, a second pipe 42, a first header 21, a second header 22, and a heat-transfer-tube-unit group 39. The heat-transfer-tube-unit group 39 includes a plurality of heat-transfer-tube units 30.

(2) Configurations of Relevant Elements (2-1) Headers and Pipes

The first pipe 41 and the second pipe 42 are provided for refrigerant to flow therethrough. The first pipe 41 and the second pipe 42 each serve as an inlet and an outlet for the refrigerant, which can be in any of different forms such as gas, liquid, and a gas-liquid two-phase form. The first pipe 41 is connected to the first header 21 so as to supply and receive the refrigerant to and from the first header 21. The second pipe 42 is connected to the second header 22 so as to supply and receive the refrigerant to and from the second header 22. The first header 21 and the second header 22 are each a hollow member and have respective heat-transfer-tube-unit-connecting surfaces 23. The first header 21 and the second header 22 are arranged such that the respective heat-transfer-tube-unit-connecting surfaces 23 face each other or substantially face each other. In one or more embodiments, the second header 22 is positioned below the first header 21.

(2-2) Heat-Transfer-Tube Unit

The plurality of heat-transfer-tube units 30 included in the heat-transfer-tube-unit group 39 are arranged side by side at intervals in a heat-transfer-tube-unit-arranging direction x. Each of the heat-transfer-tube units 30 is connected to the first header 21 and to the second header at the respective heat-transfer-tube-unit-connecting surfaces 23.

FIG. 2 illustrates one of the heat-transfer-tube units 30. The heat-transfer-tube unit 30 includes a plurality of heat transfer tubes 31 and a plurality of fins 32. The number of heat transfer tubes 31 included in the heat-transfer-tube unit 30 is, for example, six or greater but is not limited thereto.

The heat transfer tubes 31 are provided for moving the refrigerant between the first header 21 and the second header 22. Two ends of each of the heat transfer tubes 31 are connected to the heat-transfer-tube-unit-connecting surfaces 23 of the first header 21 and the second header 22, respectively. The heat transfer tube 31 includes at least a portion extending in a heat-transfer-tube-extending direction z and may have a linear shape. The plurality of heat transfer tubes 31 are arranged side by side in a heat-transfer-tube-spacing direction y.

The fins 32 are provided for heat exchange between the refrigerant flowing in adjacent ones of the heat transfer tubes 31 and ambient air. The fins 32 are each provided between adjacent two of the heat transfer tubes 31. Additional fins 32 may be provided on the outer side of outermost ones, respectively, of the heat transfer tubes 31 included in the heat-transfer-tube unit 30. The fins 32 each have sides extending in the heat-transfer-tube-extending direction z, and the sides are joined to corresponding ones of the heat transfer tubes 31. The fins 32 and the heat transfer tubes 31 are arranged alternately side by side in the heat-transfer-tube-spacing direction y. A fan or the like, not illustrated, causes air to flow in a direction parallel to a y-z plane. The direction of the airflow may be the heat-transfer-tube-spacing direction y.

The heat-transfer-tube-unit-arranging direction x, the heat-transfer-tube-spacing direction y, and the heat-transfer-tube-extending direction z intersect one another. The heat-transfer-tube-unit-arranging direction x, the heat-transfer-tube-spacing direction y, and the heat-transfer-tube-extending direction z may be perpendicular to one another. The heat-transfer-tube-unit-arranging direction x and the heat-transfer-tube-spacing direction y may each be a horizontal direction, and the heat-transfer-tube-extending direction z may be a vertical direction. FIG. 3 illustrates a section of the heat-transfer-tube unit 30. The heat transfer tubes 31 each have an inside diameter D of, for example, 1.5 mm or smaller, or 0.8 mm or smaller. The fins 32 each have a thickness T of, for example, 0.3 mm or smaller, 0.2 mm or smaller, or 0.1 mm or smaller.

(3) Connection Between Heat-Transfer-Tube Unit and Header

As illustrated in FIG. 2, the heat-transfer-tube unit 30 has cutouts 33 at ends thereof in the fins 32. The presence of the cutouts 33 makes ends 32 e of the fins 32 be positioned nearer to the center of the heat-transfer-tube unit 30 in the heat-transfer-tube-extending direction z than ends 31 e of the heat transfer tubes 31.

FIG. 4 is a sectional view of the heat exchanger 10. The second header 22 has holes 24 for insertion of the ends 31 e of the heat transfer tubes 31. The ends 32 e of the fins 32 are shaped in conformity with the shape of the second header 22 in such a manner as to be in contact with at least the heat-transfer-tube-unit-connecting surface 23 of the second header 22 with the ends 31 e of the heat transfer tubes 31 being in the holes 24. The points of contact are fixed by brazing or the like, whereby the path for the refrigerant is sealed.

While FIG. 4 illustrates the second header 22 and the periphery thereof, the first header 21 and the periphery thereof are also configured as above.

(4) Method of Manufacturing Heat Exchanger 10

The heat-transfer-tube unit 30 is manufactured from a metal material such as aluminum or an aluminum alloy. Firstly, fins 32 and heat transfer tubes 31 are integrally formed from the metal material by extrusion molding with a mold corresponding to the shape of the section illustrated in FIG. 3. Subsequently, portions of the fins 32 are removed to provide cutouts 33. Thus, the ends 32 e of the fins 32 are positioned nearer to the center of the heat-transfer-tube unit 30 in the heat-transfer-tube-extending direction z than the ends 31 e of the heat transfer tubes 31. The cutouts 33 are desirably provided by removing a plurality of portions of the fins 32 by punching.

The first header 21 and the second header 22 are each manufactured by processing a metal material into a tubular shape. The holes 24 for insertion of the ends 31 e of the heat transfer tubes 31 are formed in the first header 21 and the second header 22. The holes 24 are circular holes provided by, for example, drilling.

The heat exchanger 10 is assembled by inserting the ends 31 e of the heat transfer tubes 31 of the heat-transfer-tube unit 30 into the respective holes 24 in the first header 21 and the second header 22. Thus, the ends 32 e of the fins 32 come into contact with the heat-transfer-tube-unit-connecting surface 23 of the second header 22. The heat-transfer-tube unit 30 and the first header 21 or the second header 22 are brazed to each other at the points of contact. Specifically, brazing metal is applied in advance to the heat-transfer-tube-unit-connecting surfaces 23 of the first header 21 and the second header 22. After the ends 31 e of the heat transfer tubes 31 of the heat-transfer-tube unit 30 are inserted into the respective holes 24 in the heat-transfer-tube-unit-connecting surfaces 23, the heat exchanger 10 is put into a furnace. Thus, the brazing metal is melted and fills the gaps between the edges of the holes 24 and the respective heat transfer tubes 31.

(5) Features

(5-1)

Since the cutouts 33 are provided by removing portions of the fins 32, the ends 31 e of the heat transfer tubes 31 project from the ends 32 e of the fins 32. Therefore, the heat exchanger 10 can be manufactured easily by inserting the projecting portions of the heat transfer tubes 31 into the holes 24 in the first header 21 and the second header 22.

(5-2)

The two ends of the heat-transfer-tube unit 30 are fixed to the first header 21 and the second header 22, respectively. Therefore, the heat exchanger exhibits improved durability against external forces and impacts.

(5-3)

The ends 32 e of the fins 32 are in contact with the first header 21 and the second header 22. Therefore, the heat-transfer-tube unit 30 and each of the first header 21 and the second header 22 are connected to each other with improved strength.

(5-4)

The heat-transfer-tube unit 30 is formed as a single member from a metal material by extrusion molding. Therefore, the heat-transfer-tube unit 30 is easy to handle. Accordingly, the heat exchanger 10 is easy to assemble.

(5-5)

The plurality of cutouts 33 are provided at a time by punching. Therefore, the heat exchanger 10 is manufactured efficiently.

(5-6)

The holes in the first header 21 and the second header 22 may be provided simply by using a drill. In that case, the heat exchanger 10 is manufactured more easily.

(6) Modifications

Modifications of one or more embodiments will now be described.

(6-1) First Modification

FIG. 5 illustrates a heat exchanger 10′ according to one or more embodiments of the present invention. The heat exchanger 10′ is different from the heat exchanger 10 according to one or more embodiments in that the ends 32 e of the fins 32 are spaced apart from the heat-transfer-tube-unit-connecting surfaces 23 of the first header 21 and the second header 22. Such a configuration is realized with stoppers 35 provided on the heat transfer tubes 31. The stoppers 35 are provided between the ends 31 e of the heat transfer tubes 31 and the ends 32 e of the fins 32. The stoppers 35 are shaped in such a manner as not to be allowed to pass through the holes 24 in the first header 21 and the second header 22. A gap 36 is provided between each of the stoppers 35 and a corresponding one of the fins 32, whereby the stoppers 35 are spaced apart from the ends 32 e of the fins 32. In the first modification, the stoppers 35 are provided to all of the heat transfer tubes 31 of the heat-transfer-tube unit 30, respectively.

The stoppers 35 are formed as fins 32 at the beginning of the manufacturing process. Then, in a step of punching off portions of the fins 32 for providing cutouts 33, stoppers 35 are obtained as portions that are not punched off, and remain on the heat transfer tubes 31.

Such a configuration in which the stoppers 35 are spaced apart from the ends 32 e of the fins 32 suppresses the occurrence of a phenomenon in which the brazing metal melted in the furnace moves into spaces between the fins 32 by capillarity. Therefore, concentration of the brazing metal is suppressed, and the occurrence of erosion of the brazing metal or the fins 32 is reduced.

(6-2) Second Modification

FIG. 6 illustrates a heat exchanger 10″ according to one or more embodiments of the present invention. The heat exchanger 10″ is different from the heat exchanger 10′ in that the stoppers 35 are provided on only some of the heat transfer tubes 31 of the heat-transfer-tube unit 30.

Such a configuration further suppresses the occurrence of the phenomenon in which the brazing metal moves into spaces between the fins 32 by capillarity.

(1) Configuration

FIG. 7 illustrates a heat exchanger 10A according to one or more embodiments of the present invention. The heat exchanger 10A is configured such that at least the second header 22 has a trapezoidal sectional shape. Therefore, the heat-transfer-tube-unit-connecting surface 23 of the second header 22 is inclined with respect to the heat-transfer-tube-spacing direction y. The ends 32 e of the fins 32 are shaped in conformity with the shape of the second header 22 in such a manner as to be in contact with at least the heat-transfer-tube-unit-connecting surface 23 of the second header 22 with the ends 31 e of the heat transfer tubes 31 being in the holes 24.

Such a configuration causes dew condensation water running down the heat-transfer-tube unit 30 and reaching the heat-transfer-tube-unit-connecting surface 23 to further run down the second header 22 because of the inclination. Therefore, the heat exchanger 10A exhibits improved drainability.

(2) Modifications

The modifications of one or more above embodiments may be applied to one or more following embodiments.

(1) Configuration

FIG. 8 illustrates a heat exchanger 10B according to one or more embodiments of the present invention. The heat exchanger 10B is configured such that at least the second header 22 has a sectional shape pointed upward. Therefore, the heat-transfer-tube-unit-connecting surface 23 of the second header 22 includes two inclined surfaces inclining with respect to the heat-transfer-tube-spacing direction y. The ends 32 e of the fins 32 are shaped in conformity with the shape of the second header 22 in such a manner as to be in contact with at least the heat-transfer-tube-unit-connecting surface 23 of the second header 22 with the ends 31 e of the heat transfer tubes 31 being in the holes 24.

Such a configuration also causes dew condensation water running down the heat-transfer-tube unit 30 and reaching the heat-transfer-tube-unit-connecting surface 23 to further run down the second header 22 because of the inclination. Therefore, the heat exchanger 10B exhibits improved drainability.

(2) Modifications

The modifications of one or more above embodiments may be applied to one or more following embodiments.

(1) Configuration

FIG. 9 illustrates a heat exchanger 10C according to one or more embodiments of the present invention. The heat exchanger 10C is configured such that at least the second header 22 is a circular pipe. Therefore, most part of the heat-transfer-tube-unit-connecting surface 23 of the second header 22 is inclined with respect to the heat-transfer-tube-spacing direction y. The ends 32 e of the fins 32 are shaped in conformity with the shape of the second header 22 in such a manner as to be in contact with at least the heat-transfer-tube-unit-connecting surface 23 of the second header 22 with the ends 31 e of the heat transfer tubes 31 being in the holes 24.

In such a configuration, since at least the second header 22 is a circular pipe, the second header 22 is easy to manufacture. Therefore, the heat exchanger 10 can be manufactured more easily.

In addition, since the heat-transfer-tube-unit-connecting surface 23 of the second header 22 is inclined, dew condensation water running down the heat-transfer-tube unit 30 and reaching the heat-transfer-tube-unit-connecting surface 23 further runs down the second header 22. Therefore, the heat exchanger 10C exhibits improved drainability.

(2) Modifications

The modifications of one or more above embodiments may be applied to one or more following embodiments.

(1) Configuration

FIG. 10 illustrates a heat exchanger 10D according to one or more above embodiments of the present invention. The heat exchanger 10D is configured such that the first header 21 and the second header 22 are provided on the same side of the heat-transfer-tube-unit group 39. The first header 21 and the second header 22 are connected to the first pipe 41 and the second pipe 42, respectively.

FIG. 11 illustrates one of a plurality of heat-transfer-tube units 30 included in the heat-transfer-tube-unit group 39 of the heat exchanger 10D. The heat-transfer-tube unit 30 includes a plurality of heat transfer tubes 31 and at least one fin 32. The heat transfer tubes 31 each include at least a portion extending in the heat-transfer-tube-extending direction z and each may have a linear shape. The plurality of heat transfer tubes 31 are arranged side by side in the heat-transfer-tube-spacing direction y. Furthermore, adjacent ones of the heat transfer tubes 31 are coupled to each other with a curved coupling pipe 31 c. That is, the heat-transfer-tube unit 30 has a single refrigerant path formed of the heat transfer tubes 31 and the coupling pipes 31 c. The refrigerant path allows the refrigerant to move between the first header 21 and the second header 22. The ends 31 e of the heat transfer tubes 31 are connected to the heat-transfer-tube-unit-connecting surfaces 23 of both the first header 21 and the second header 22.

The heat-transfer-tube unit 30 includes the fin 32 that is present between adjacent ones of the heat transfer tubes 31. Additional fins 32 may be provided on the outer side of outermost ones, respectively, of the heat transfer tubes 31 of the heat-transfer-tube unit 30. Such a plurality of fins 32 may be connected to one another at the upper end or the lower end of the heat-transfer-tube unit 30. The fins 32 each have sides extending in the heat-transfer-tube-extending direction z, and the sides are joined to corresponding ones of the heat transfer tubes 31. The fins 32 and the heat transfer tubes 31 are arranged alternately side by side in the heat-transfer-tube-spacing direction y. A fan or the like, not illustrated, causes air to flow in a direction parallel to the y-z plane. The direction of the airflow may be the heat-transfer-tube-spacing direction y. The heat-transfer-tube unit 30 may be manufactured by a method other than extrusion molding of a metal material.

The heat-transfer-tube unit 30 has cutouts 33 at ends thereof in the fins 32. The presence of the cutouts 33 makes ends 32 e of the fins 32 be positioned nearer to the center of the heat-transfer-tube unit 30 in the heat-transfer-tube-extending direction z than ends 31 e of the heat transfer tubes 31. The ends 32 e of the fins 32 are shaped in conformity with the shapes of the first header 21 and the second header 22 in such a manner as to be in contact with the heat-transfer-tube-unit-connecting surfaces 23 with the ends 31 e of the heat transfer tubes 31 being in the holes 24 in the first header 21 and the second header 22. The points of contact are fixed by brazing or the like, whereby the refrigerant path is sealed.

Such a configuration allows three of the four sides of the heat-transfer-tube unit 30 to be open to a peripheral space. Therefore, dew condensation water is drained more easily.

(2) Modifications

The modifications of one or more above embodiments may be applied to one or more following embodiments.

One or more embodiments described above concern an exemplary arrangement in which the heat-transfer-tube-unit-arranging direction x and the heat-transfer-tube-spacing direction y are each a horizontal direction, and the heat-transfer-tube-extending direction z is a vertical direction. Alternatively, the heat exchanger 10 may be oriented in another way. For example, the heat-transfer-tube-spacing direction y and the heat-transfer-tube-extending direction z may each be a horizontal direction, and the heat-transfer-tube-unit-arranging direction x may be a vertical direction.

Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims.

REFERENCE SIGNS LIST

-   -   10 heat exchanger     -   21 first header     -   22 second header     -   23 heat-transfer-tube-unit-connecting surface     -   24 hole     -   30 heat-transfer-tube unit     -   31 heat transfer tube     -   31 e end of heat transfer tube     -   32 fin     -   32 e end of fin     -   33 cutout     -   35 stopper     -   36 gap     -   41 first pipe     -   42 second pipe 

1.-12. (canceled)
 13. A heat exchanger comprising: a heat-transfer-tube unit comprising a fin and heat transfer tubes; and a header connected to the heat-transfer-tube unit, wherein the fin and the heat transfer tubes are disposed, alternately, side by side, wherein the heat transfer tubes extend in a heat-transfer-tube-extending direction, wherein the fin has sides that extend in the heat-transfer-tube-extending direction and that are joined to the heat transfer tubes, wherein an end of the fin is disposed closer to a center of the heat-transfer-tube unit in the heat-transfer-tube-extending direction than ends of the heat transfer tubes, and wherein the ends of the heat transfer tubes are inserted into holes disposed on the header.
 14. The heat exchanger according to claim 13, wherein the header comprises a first header and a second header, and the heat-transfer-tube unit is held between the first header and the second header.
 15. The heat exchanger according to claim 14, wherein the second header is disposed below the first header, and the second header comprises a heat-transfer-tube-unit-connecting surface inclined with respect to a heat-transfer-tube-spacing direction.
 16. The heat exchanger according to claim 13, wherein the header is a circular pipe.
 17. The heat exchanger according to claim 13, wherein the end of the fin conforms with a shape of the header and contacts the header when the ends of the heat transfer tubes are inserted in the holes.
 18. The heat exchanger according to claim 13, wherein the end of the fin is spaced apart from the header.
 19. The heat exchanger according to claim 18, wherein the heat-transfer-tube unit further comprises: stoppers disposed on the heat transfer tubes and between the ends of the heat transfer tubes and the end of the fin, and the stoppers are shaped so that the stoppers cannot pass through the holes in the header.
 20. The heat exchanger according to claim 13, wherein the heat-transfer-tube unit is a single member.
 21. A heat exchanger manufacturing method, comprising: forming a heat-transfer-tube unit comprising a fin and heat transfer tubes; forming a cutout by removing a portion of the fin, wherein an end of the fin is disposed closer to a center of the heat-transfer-tube unit in a heat-transfer-tube-extending direction than ends of the heat transfer tubes; forming holes in a header; inserting the ends of each of the heat transfer tubes into respective ones of the holes; and brazing the heat-transfer-tube unit and the header to one another other.
 22. The heat exchanger manufacturing method according to claim 21, wherein the forming of the heat-transfer-tube unit comprises integrally forming the fin and the heat transfer tubes from a metal material by extrusion molding.
 23. The heat exchanger manufacturing method according to claim 21, wherein portions of the fin are punched off in the forming of the cutout.
 24. The heat exchanger manufacturing method according to claim 21, wherein the holes are formed by drilling. 